Summary: The Expert Consensus on DNA Methylation Sample Processing and Detection, jointly compiled by the Professional Committee of Laboratory Medicine of the Chinese Association of Integrative Medicine, the Molecular Diagnostics Group of the Chinese Society of Laboratory Medicine, and the Precision Medicine Committee of the Beijing Association of Integrative Medicine, was officially published in the Chinese Journal of Preventive Medicine (2026, Vol.60, No.8). Covering four key stages — sample collection, nucleic acid extraction and conversion, methylation detection, and result reporting — the consensus formulates 14 recommendations, establishing China's first full-process standard for methylation testing. Digital PCR (dPCR) is listed as a strongly recommended method: suitable for precise quantification of low-abundance DNA and absolute quantification of methylation levels, with sensitivity down to 0.01% or lower. This recommendation precisely underlines the irreplaceable role of digital PCR in the era of epigenetic testing.
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01 Methylation Testing: A "Must-Have" for Low-Abundance Scenarios
DNA methylation is one of the earliest molecular events in tumorigenesis. With its early occurrence, dynamic reversibility and relative stability, it has become a star biomarker for early cancer screening. However, its detection inherently faces two major challenges:
Extremely low sample input — Liquid biopsy relies on cfDNA, which is present in very small amounts. After bisulfite conversion, about 90% of DNA is degraded, leaving very little template for the actual detection.
Extremely low target fraction — Methylated ctDNA released by early-stage tumors may account for only 0.01%–0.1% of total cfDNA.
The mainstream route recommended by the consensus — magnetic-bead extraction, bisulfite conversion, and PCR detection — places stringent demands on sensitivity and interference resistance. Digital PCR partitions a sample into tens of thousands to millions of independent reaction units and directly "counts molecules": it delivers absolute copy numbers without a standard curve and is unaffected by amplification efficiency fluctuation — naturally suited to this "needle in a haystack" type of detection. The consensus also notes that MethyLight is suitable for large-sample screening, while digital PCR offers greater advantages in precise low-abundance quantification — the two complement each other and together form the recommended technical combination for clinical methylation testing.
02 MRD Monitoring: The Clinical Value of Absolute Quantification
Minimal Residual Disease (MRD) has become a hot topic in oncology in recent years. After curative surgery, about 20%–30% of colorectal cancer patients still relapse within 5 years, and positive ctDNA MRD results often predict recurrence 3–10 months earlier than imaging. Post-operative ctDNA abundance is extremely low — precisely within the sensitivity range of digital PCR:
Baseline tracking — Collect once after surgery, then monitor periodically with the same panel.
Trend interpretation — dPCR provides continuous, laterally comparable absolute copy numbers: declining abundance suggests effective treatment, while persistent or new positivity signals relapse risk.
Decision support — In studies such as DYNAMIC, adjuvant chemotherapy escalation for ctDNA-positive patients and de-escalation for ctDNA-negative patients have gained high-level evidence support.
China's Expert Consensus on Detection and Clinical Application of Common Biomarkers in Lung Cancer (2026 Edition) likewise points out that digital PCR offers stronger interference resistance and higher sensitivity, is mainly suitable for low-abundance methylation detection, and recommends dynamic ctDNA quantification and MRD analysis — multiple consensus documents are jointly positioning dPCR as a core tool for MRD monitoring.
03 Liquid Biopsy: A "Molecular Radar" Across the Whole Journey
With a half-life of only 1–2 hours, ctDNA reflects tumor burden changes in real time — making liquid biopsy inherently suitable for dynamic monitoring. Methylation biomarkers combine high tissue specificity, delivering dual value of "detection + tracing". From early screening and auxiliary diagnosis to efficacy evaluation and relapse monitoring, digital PCR — with its combination of low cost, fast turnaround and high sensitivity — has become one of the most clinically accessible liquid biopsy platforms.
From early cancer screening to post-operative MRD management and dynamic monitoring across the whole disease course, clinical adoption of methylation testing is accelerating. The release of this consensus defines the technical route for the industry and reconfirms that for the core needs of low abundance and absolute quantification, digital PCR is the key answer. Bringing precise molecular testing into more laboratories is exactly what "popularizing digital PCR" means.
References
1. Professional Committee of Laboratory Medicine, Chinese Association of Integrative Medicine, et al. Expert Consensus on DNA Methylation Sample Processing and Detection [J]. Chinese Journal of Preventive Medicine, 2026, 60(8): 1217-1235.
2. Tumor Biomarker Committee, Chinese Anti-Cancer Association. Expert Consensus on Detection and Clinical Application of Tumor DNA Methylation Biomarkers (2024 Edition) [J]. Chinese Journal of Cancer Prevention and Treatment, 2024.
3. Chinese Society of Laboratory Medicine. Expert Consensus on Detection and Clinical Application of Common Biomarkers in Lung Cancer (2026 Edition) [J]. Chinese Journal of Laboratory Medicine, 2026, 49(5): 530-545.
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